Authorities are investigating the cause of an explosion aboard a cargo ship that was leaving the Port of Baltimore when it issued a mayday call.

The blast happened near the site of last year's deadly Francis Scott Key Bridge collapse, the Coast Guard said, and the resulting fire was extinguished.

An explosion erupted on a cargo ship hauling coal in Baltimore’s harbor near the Key Bridge collapse site Monday evening, according to news sources. The explosion, which has been fully contained, started at 6:28 p.m., Baltimore City fire officials told WBALTV11. The ship was full of coal and had just left the CSX Coal Dock.